You can say that again!

you can say that again

I agree completely; what you said is especially true. A: "Wow, that exam was brutally difficult." B: "You can say that again! It was the hardest test I've ever taken."
See also: again, can, say, that
Farlex Dictionary of Idioms.

You can say that again!

 and You said it!
Inf. That is true.; You are correct. (The word that is emphasized.) Mary: It sure is hot today. Jane: You can say that again! Bill: This cake is yummy! Bob: You said it!
See also: can, say, that
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

you can say that again!

used to express emphatic agreement. informal
See also: can, say, that
Farlex Partner Idioms Dictionary

you can say ˈthat again!

(spoken) I agree completely; I know that already: ‘She’s the most boring person I’ve ever met.’ ‘You can say that again!’
See also: can, say, that
Farlex Partner Idioms Dictionary

You can say that again!

exclam. I agree! You can say that again! You hit the nail right on the head.
See also: can, say, that
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • you can say that again
  • you said it
  • you said it!
  • no kidding
  • No kidding!
  • everything is coming up roses
  • everything's coming up roses
  • be in ruins
  • bear a resemblance to
  • bear a resemblance to (someone or something)